If its stage 2 hotcams you need the valve spring kit with it.
A higher compression piston is usually recommended to help bump up the low rpm horsepower your going to lose. You can run a 11:1 piston on pump gas.
Unless you have mechanical experience, I would recommend having a professional install it. You can buy a factory service manual which shows all the parts and pieces and how they go together. Then you can decide from there if ou want to give it a whirl.
That depends on what your ultimate goals are. If you plan on going with a high compression piston, I would suggest the stage 2. But if you're not looking to spend a whole lot of money (because the stage 2 requires new springs) then go with the stage one.